diff --git a/src/Protocol/Protocol18x.cpp b/src/Protocol/Protocol18x.cpp
index 1d83be8dd..17faca27e 100644
--- a/src/Protocol/Protocol18x.cpp
+++ b/src/Protocol/Protocol18x.cpp
@@ -51,7 +51,7 @@ Implements the 1.8.x protocol classes:
 
 
 /** The slot number that the client uses to indicate "outside the window". */
-static const Int16 SLOT_NUM_OUTSIDE = -999;
+static const Int16 SLOT_NUM_OUTSIDE = -1;